Explosive compositions and processes for producing explosions on surfaces



United Stes EXPLOSIV E COMPOSITIONS AND PROCESSES FOR PRODUCING EXPLOSIONS N SURFACES James W. Perry, 219 Langley Road, Newton Centre, Mass.; Joseph H. Frazer, RD. 2, Havre de Grace, Md.; and William R. Johnson, 1305 14th St., Texas City,

No Drawing. Filed Oct. 31, 1947, Ser. No. 783,429

4 Claims. (Cl. 52-1) (Granted under Title 35,;Code (1952), see. 266) clearing mine fields, concrete demolition and in general where the use of an explosive over a considerable open area is desired. Explosives of this type can be sprayed or otherwise spread over the area to be affected and exploded by detonation.

A path can be provided through mine fields by spraying the explosive mixture on the ground to be cleared whereupon a blasting cap, high explosive shell, grenade or other detonating device can be set off in the explosive which will then be detonated producing a pressure wave directed downward from the surface of the ground. Buried mines under the pressure wave Will be exploded or at least have the firing mechanism thereof smashed rendering the mines useless.

For maximum performance the explosive should be a viscous thixotropic liquid which will gel on standing undisturbed. Such a mixture can be sprayed and spreads out into a thin, even layer on striking the ground and remain evenly spread out for a considerable period of time without undergoing appreciable change. It is highly desirable to ensure that the explosive mixture remains evenly spread in order to achieve effective destruction over the entire area to which it is applied. The addition of a thickener to the mix keeps the explosive spread out as a thin layer and prevents it from collecting as puddles in depressions in the ground. Further, the presence of a thickener inhibits diffusion of water from wet ground in the layer of explosive thereby preventing a reduction in the sensitivity of the explosive.

It is known that the eifectiveness against concrete of a given weight of an explosive charge is increased when the explosive is spread over a relatively large area of the concrete. It is therefore desirable to provide an explosive that can be projected in the form of a relatively stiif jelly onto a concrete structure to be destroyed, in layers of moderate thickness, that is about one to four inches, and then detonated.

It is further preferable that explosives of the type hereinbefore described can be easily and quickly prepared by mixing together liquids which are individually safer to handle than the complete explosive mixture. Such liquids can be mixed together at the time when it is desired to use the explosive by, for example, spraying the liquids separately, but from a single nozzle or introducing the liquids in the nozzle and then spraying the resulting mixture.

It is therefore the principal object of the present invention to provide an explosive in the form of a highly viscous liquid or plastic solid which can be produced by a mixatent ture of liquids each of which are individually relatively safe to handle.

A further and important object of the invention is to provide an explosive which can be spread as a thin layer over a surface and which explosive will remain evenly spread and will not readily absorb moisture from its surroundings.

A still further object of the invention is to provide an explosive mixture which can be formulated as a viscous thixotropic liquid or as arelatively stiff jelly for application over large areas and which can be exploded by detonat-ion.

High explosives meeting the objects of the present in vention can be produced by mixing the following:

(1) A concentrated perchloric acid.

(2) A liquid fuel material miscible with the perchloric acid, such as a glycol or aliphatic glycol derivative.

(3) A thickening agent comprising a colloidal substance of high molecular weight.

The thickening agent is dissolved in the liquid fuel and the resulting solution can be mixed with the perchloric acid at such time as it is desired to employ the explosive mixture.

Additional examples of suitable liquid fuels among others are ethylene glycol, propylene glycol and their aliphatic derivatives which include commercial products having the following formulas:

The foregoing products are characterized by:

(1) Miscibility with concentrated perchloric acid.

(2) Stability at ordinary temperatures of the solution when mixed with concentrated perchloric acid.

( 3) Relatively high heat of combustion.

(4) Relatively slow evaporation rate which makes it possible to spread the explosive composition out in a thin layer and detonate it before the composition has changed appreciably due to evaporation.

(5 Good solvent power for high molecular weight substances.

(6) Existing in the liquid state at room temperature and at temperatures ordinarily encountered outdoors.

Various other materials having the foregoing characteristics may equal as well be used in place of the glycols and their derivatives.

Examples of thickeners which can be employed in forming the explosive are ethyl cellulose or benzly cellulose. Colloidal substances of high molecular weight in general capable of imparting either a high viscosity or a jelly-like consistence to the explosive mixture can be employed for the present purpose.

Examples of explosive mixtures formulated in accordance with the present invention are hereinafter described.

Dissolve sufiicient ethyl cellulose in monoethyl ether of ethylene glycol to provide a 6% ethyl cellulose solution. Dilute the resulting solution in an equal amount of additional monoethyl ether of ethylene glycol. Mix 1.0 part by volume of the diluted solution thoroughly with 1.5 parts of concentrated perchloric acid. The resulting mixture is a gelatinous semi-solid mass which is thixotropic. On shaking, the mass assumes the physical characteristics of a viscous fluid which on standing undisturbed rapidly resumes the form of a semi-solid opalescent gel. This mixture can be spread over the ground and detonated by using a blasting cap placed in contact with the mixture at one edge thereof.

A further example of the explosive is produced by preparing an 8% solution of benzyl cellulose in monobutyl ether of ethylene glycol by dissolving the benzyl cellulose inthe lyccl ,W jle heating toabout 70 C. and then shaking to hasten solution. 1.0 parts by volume'of. the resultingsolution is then mixed with 1.5 parts of perchloric acid of a 70-72% concentration. The resulting mixture is thick, but notthixotropic andthe' benzyl cellulose is less highly s'olvatedthanthe ethyl cellulose of the previous example.

Aistill further example can beproduced by preparing a 4%, solution. of ethyl cellulose in monoethyl ether of ethylene glycol. Thesolution sho'ud be shaken; then allowed to stand for about 12 hours andthen again thc roughly shaken to ensure homogeneity. The explosive mixture, is then prepared by mixing 1.0 part by volume of the resultingsqlution with 1.5, parts, of perchloric acid of about one partby volume ofjanabout 4 percent solution of 70-72% solution. is carried out by a stirring the solution andthe acid together with the acid being added in three to five approximately equal portions. The mixture is cooled thoroughly between additions of successive increments of the perchloric'acid.

In theforegoing examples the perchloric acid is referred to asbeing as of a 70-72% concentration. Of course other concentrations can be used, but it has been found that in mixture using a lower concentration the explosive force of the mixture is reduced. On; the other hand an, acid of a higher concentration produces an explosive which is ,more sensitive. and therefore less desirable to use.

The foregoing explosive 'mixtures are described as examples of the present invention-whereby others skilled in the art can make and use the same. However, these examples are not to be construedas limiting the invention as it is known that an explosive having the characteristics desired; can be produced through the combining of the various classes of ingredients referred to'in many difierent combinations and therefore any mixture coming of ethyl cellulose in a material selected from the group consisting of ethylene glycol, propylene glycol and aliphatic derivatives of ethylene glycol and propylene glycol, and about oneand a half parts by volume of an aqueous solution of. perchloric acid containingifrom about 70' to 72 percent of perchloric acid.v

3. In, the art of producing explosions upon a surface wherein-a detonable liquid mixture comprising a concentrated aqueousvsolution of perchloric acd and a material a selected from thelgroup consistingof ethylene glycol,

propylene glycol and. aliphatic derivatives ofethylene glycol and propylene glycol isspread upon, said surface and thereafter detonated, the-step of incorporating in the said detonabl'e: liquid mixture, priorto. spreading it upon said surface, a cellulose .ethiertothickeri the said mixture.

4. Theinventiomdefinedinclaim 3 wherein the. cellulose. ethery cellulose.

I References Cited in the file of this patent" UNITED STATES PATENTS' Wfight 1. Apr; 6, 1948 7 OTHER REFERENCES Chem. Ztg.-, ol.66,.page-415. (1942). Chem. ZtgJ, page1361 .(1943). 

1. A HIGH EXPLOSIVE CONSISTING ESSENTIALLY OF A MIXTURE OF ABOUT ONE PART BY VOLUME OF AN ABOUT 4 PERCENT SOLUTION OF A CELLULOSE ETHER IN A MATERIAL SELECTED FROM THE GROUP CONSISTING OF ETHYLENE GLYCOL, PROPYLENE GLYCOL AND ALIPHATIC DERIVATIVES OF ETHYLENE GLYCOL AND PROPYLENE GLYCOL, AND ABOUT ONE AND A HALF PARTS BY VOLUME OF AN AQUEOUS SOLUTION OF PERCHLORIC ACID CONTAINING FROM ABOUT 70 TO 72 PERCENT OF PERCHLORIC ACID. 